1. Field of the Invention
The present invention relates generally to handwriting data entry, and more particularly to methods and systems for facilitating data entry using a pen input device.
2. Description of the Related Art
Digital writing instruments, interchangeably referred to herein as xe2x80x9cdigital pensxe2x80x9d regardless of whether they write in ink, can be used to capture pen strokes on paper and digitize them, so that the pen strokes can be converted by handwriting recognition software to a digitally-stored record of the writing. In this way, a laborious, tedious step in modern written communication, namely, the manual transcribing of handwriting into a computerized word processor, is eliminated, greatly increasing productivity.
Accordingly, digital pen systems can digitize pen strokes across a substrate, by sensing, in some fashion, the time-dependent position of the pen and converting the positions to pen strokes, for input of digital representations of the pen strokes to a handwriting recognition device. As recognized herein, magnetic-type systems can be used in which a special pen generates or alters a magnetic field as it is moved across a piece of paper, with the field being sensed by a special pad over which the paper is placed. Similarly, ultrasonic systems can be used in which a special pen generates or alters an ultrasonic signal as the pen is moved across a piece of paper, with the signal being sensed by a special pad over which the paper is placed.
Another type of pen input device has been developed by OTM Technologies Ltd. of Israel under the trade name xe2x80x9cOTMxe2x80x9d technology, which uses interference patterns generated by laser reflections from a substrate to track relative pen position. As recognized herein, the OTM technology does not contemplate absolute pen position tracking, such that if the pen is lifted from the substrate and placed back down to, e.g., cross a xe2x80x9ctxe2x80x9d or dot an xe2x80x9cixe2x80x9d, it is not known where the pen is placed, relative to where it was lifted off the substrate. This is undesirable from a user""s viewpoint.
Moreover, since the pen tip must be used to write on the substrate, the laser cannot be placed right on the tip, but only nearby. This can create parallax between the tip, the position of which is desired, and the source of the light from which the position is actually derived. If a writer rotates the pen while leaving the tip in one place on the substrate, the parallax causes positional errors.
The present invention recognizes both of the above-noted problems and is directed to solving at least one of them.
A digital pen includes an elongated body defining a writing tip and a laser oriented on the body to direct light onto a substrate against which the writing tip can be positioned. A diffraction grating on the body reflects a reference beam and passes a scattered beam from the substrate, with these beams being received by at least one and preferably three translation detectors as interference patterns of light. Also, a bar code detector on the body receives a bar code beam from the substrate, and a processor receives signals from the detectors and stores them for later uploading to a host processor.
In a preferred embodiment, the processor is programmed to output position signals representative of positions of the pen. In addition to the light detectors, the pen body can support a force sensor that outputs a signal representative of multidimensional forces applied to the pen. A digital memory is supported by the body and it stores position and force signals from the processor, whereby the signals can be retrieved from the memory and processed by the host processor. Preferably, a filter circuit includes filtering structure to remove speckle contributions to the signal from the bar code detector.
In a preferred embodiment, the substrate includes optical codes known to the host processor. In this embodiment, the bar code detector outputs a signal in response to detecting an optical code, and the host processor combines data generated by the bar code detector with data generated by the translation detectors to render absolute pen positions. The processor further uses data from the force sensor to correct for pen rotation. In contrast, when the substrate does not include optical codes known to the host processor, the host processor combines data generated by the force sensor with data generated by the translation detectors to render rotation-corrected relative pen positions.
In another aspect, a digital pen includes an elongated body defining a writing tip. A laser is oriented on the body to direct light onto a substrate against which the writing tip can be positioned, and a diffraction grating reflects a reference beam and passes scattered beams from the substrate toward at least one translation detector. Also, a force sensor is supported by the body to output a signal representative of a force applied to the pen, including static, dynamic, and acceleration. A processor receives signals from the translation detector and force sensor.
In still another aspect, a host processor is disclosed for receiving from a digital pen bar code detector data, force sensor data, and translation detector data. The host processor includes logic means for determining whether a known bar code was sensed by the pen, and logic means for, if a known bar code was sensed by the pen, combining bar code detector data with the force sensor data and translation detector data to render absolute pen positions corrected for pen rotation. Also, the host processor includes logic means for, if a known bar code was not sensed by the pen, combining force sensor data and translation detector data to render relative pen positions corrected for pen rotation.
The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: